There are threads on Bimmerpost specifically dedicated to renders/ spyshots of the new M3 sedan, including some cool, recent spy videos.
Go to this section of Bimmerpost: http://www.f30post.com/forums/forumdisplay.php?f=380
Present: 2013 M3 coupe (Azurite Black, Black, Piano Black)
Past: 2010 335i coupe (Monaco Blue, Cream Beige, Grey Poplar)
+ miata nut (2004 GT/LS and 2013 GS/Club Edition)